Vulnerability in core server (CVE-2023-2455)

Row security policies disregard user ID changes after inlining

While CVE-2016-2193 fixed most interaction between row security and user ID changes, it missed a scenario involving function inlining. This leads to potentially incorrect policies being applied in cases where role-specific policies are used and a given query is planned under one role and then executed under other roles. This scenario can happen under security definer functions or when a common user and query is planned initially and then re-used across multiple SET ROLEs. Applying an incorrect policy may permit a user to complete otherwise-forbidden reads and modifications. This affects only databases that have used CREATE POLICY to define a row security policy.

The PostgreSQL project thanks Wolfgang Walther for reporting this problem.